Donna: But it’s better than that though! Don’t you see what he’s trying to give you. Tell her, go on.
Human Doctor: I look like him, I think like him. Same memories, same thoughts, same everything. Except, i’ve only got one heart.
Rose: Which means?
Human Doctor: I’m part human. Specifically the aging part. I’ll grow old and never regenerate. I’ve only got one life, Rose Tyler. I could spend it with you. If you want.
Rose: You’ll grow old at the same time as me?
Human doctor: Together.